U.S. patent number 8,986,565 [Application Number 13/504,185] was granted by the patent office on 2015-03-24 for heat-ray shielding composition and method for producing the same.
This patent grant is currently assigned to Mitsubishi Materials Corporation, Mitsubishi Materials Electronic Chemicals Co., Ltd.. The grantee listed for this patent is Megumi Narumi, Shinya Shiraishi. Invention is credited to Megumi Narumi, Shinya Shiraishi.
United States Patent |
8,986,565 |
Shiraishi , et al. |
March 24, 2015 |
Heat-ray shielding composition and method for producing the
same
Abstract
Disclosed are a heat-ray shielding composition including an
indium tin oxide powder which has a BET specific surface area of 40
m.sup.2/g or more and a navy blue or cobalt blue (L=30 or less,
a<0, b<0 in the Lab colorimetric system) tone, and preferably
a heat-ray shielding composition, wherein the indium tin oxide
powder contained in the composition is an indium tin oxide powder
which is surface-modified by firing indium tin hydroxide having
bright yellow to persimmon (reddish brown or orange-red) tone, or
an indium tin oxide powder which is surface-modified by firing
indium tin oxide having bright yellow to persimmon (reddish brown
or orange-red) tone; and a method for producing the same.
Inventors: |
Shiraishi; Shinya (Akita,
JP), Narumi; Megumi (Kamisu, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Shiraishi; Shinya
Narumi; Megumi |
Akita
Kamisu |
N/A
N/A |
JP
JP |
|
|
Assignee: |
Mitsubishi Materials
Corporation (Tokyo, JP)
Mitsubishi Materials Electronic Chemicals Co., Ltd.
(Akita-shi, JP)
|
Family
ID: |
43922111 |
Appl.
No.: |
13/504,185 |
Filed: |
October 28, 2010 |
PCT
Filed: |
October 28, 2010 |
PCT No.: |
PCT/JP2010/069194 |
371(c)(1),(2),(4) Date: |
April 26, 2012 |
PCT
Pub. No.: |
WO2011/052689 |
PCT
Pub. Date: |
May 05, 2011 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20120211692 A1 |
Aug 23, 2012 |
|
Foreign Application Priority Data
|
|
|
|
|
Oct 29, 2009 [JP] |
|
|
2009-248627 |
Jul 29, 2010 [JP] |
|
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2010-171192 |
|
Current U.S.
Class: |
252/62;
106/401 |
Current CPC
Class: |
C09D
5/18 (20130101); C09D 7/61 (20180101); C01G
19/00 (20130101); Y10T 428/2982 (20150115); C08K
3/22 (20130101); C01P 2004/04 (20130101); C08K
2003/2231 (20130101); C01P 2006/60 (20130101); C01P
2006/32 (20130101); C01P 2006/22 (20130101); C01P
2002/72 (20130101) |
Current International
Class: |
C01G
19/00 (20060101); C09D 5/00 (20060101); C01G
15/00 (20060101) |
Field of
Search: |
;106/401 ;252/62 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
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1468856 |
|
Jan 2004 |
|
CN |
|
19840527 |
|
Mar 2000 |
|
DE |
|
0604969 |
|
Jul 1994 |
|
EP |
|
06-293515 |
|
Oct 1994 |
|
JP |
|
08-041441 |
|
Feb 1996 |
|
JP |
|
2715859 |
|
Feb 1998 |
|
JP |
|
2001-261336 |
|
Sep 2001 |
|
JP |
|
2003-215328 |
|
Jul 2003 |
|
JP |
|
2005-232399 |
|
Sep 2005 |
|
JP |
|
2005-322626 |
|
Nov 2005 |
|
JP |
|
2007-154152 |
|
Jun 2007 |
|
JP |
|
2008-110915 |
|
May 2008 |
|
JP |
|
WO2010/003743 |
|
Jan 2010 |
|
WO |
|
Other References
Machine Translation of Japanese Patent Specification No. JP
08-041441 A (Feb. 1996). cited by examiner .
Machine Translation of Japanese Patent Specification No. JP
2001-261336 A (Sep. 2001). cited by examiner .
Machine Translation of Japanese Patent Specification No. JP
2005-232399 A (May 2008). cited by examiner .
Office Action mailed Jul. 19, 2013, issued for the Chinese patent
application No. 201080048388.2 and English translation of the
search report. cited by applicant .
Hammarberg, E. et al., Microwave-assisted synthesis of indium tin
oxide nanocrystals in polyol media and transparent, conductive
layers thereof, Thin Solid Films, Elsevier-Sequoia S.A.Lausanne,
CH, vol. 516, No. 21, Sep. 1, 2008, pp. 7437-7442. cited by
applicant .
Office Action mailed Mar. 7, 2014, issued for the European patent
application No. 10826821.0. cited by applicant .
Kagaku Daijiten (Encyclopedic Dictionary of Chemistry), 1st Edition
(Tokyo Kagaku Dozin Co. Ltd.), Oct. 20, 1989, pp. 1169-1170 and
partial translation thereof. cited by applicant .
International Search Report dated Feb. 8, 2011, issued for
PCT/JP2010/069194. cited by applicant .
Search Report dated Mar. 1, 2013, issued for the European Patent
Application No. 10826821.0. cited by applicant.
|
Primary Examiner: Green; Anthony J
Attorney, Agent or Firm: Locke Lord LLP Armstrong, IV; James
E. DiCeglie, Jr.; Nicholas J.
Claims
The invention claimed is:
1. A heat-ray shielding composition comprising an indium tin oxide
powder which has a BET specific surface area of 40 m.sup.2/g or
more and a navy blue or cobalt blue (L=30 or less, a<0, b<0
in the Lab colorimetric system) tone, wherein a peak of the (222)
plane in an X-ray diffraction chart has a relative intensity of
about 2,800 to 5,000 cps, and has half value width of a peak of
about 0.3 to 0.5.degree. in the indium tin oxide powder.
2. The heat-ray shielding composition according to claim 1, the
heat-ray shielding composition further comprising a dispersion
solvent, wherein, the heat-ray shielding composition has a sunlight
transmittance of 60% or less, a visible light transmittance of 85%
or more, and a haze of 0.5% or less; as determined by: preparing a
cell an optical path length of 1 mm comprising the heat-ray
shielding composition containing the indium tin oxide powder in a
concentration of 0.7% by weight to 1.2% by weight; and measuring
the sunlight transmittance, the visible light transmittance, and
the haze through the cell.
3. The heat-ray shielding composition according to claim 1, wherein
the indium tin oxide powder contained in the heat-ray shielding
composition is an indium tin oxide powder which is surface-modified
by firing indium tin hydroxide having a bright yellow to persimmon
(reddish brown or orange-red) tone, or an indium tin oxide powder
which is surface-modified by firing indium tin oxide having a
bright yellow to persimmon (reddish brown or orange-red) tone.
4. The heat-ray shielding composition according to claim 2, wherein
the indium tin oxide powder contained in the heat-ray shielding
composition is an indium tin oxide powder which is surface-modified
by firing indium tin hydroxide having a bright yellow to persimmon
(reddish brown or orange-red) tone, or an indium tin oxide powder
which is surface-modified by firing indium tin oxide having a
bright yellow to persimmon (reddish brown or orange-red) tone.
5. The heat-ray shielding composition according to claim 1, wherein
a ratio [(ab)/L] of the (ab) value to the L value is 0.3 or
more.
6. A method for producing a heat-ray shielding composition, which
comprises the steps of: mixing an indium compound and a divalent
tin compound, co-precipitating an indium tin hydroxide in a
presence of alkali and in a solution having a pH of 4.0 to 9.3 and
a liquid temperature of 5.degree. C. or higher; drying and firing
the indium tin hydroxide to obtain a surface-modified indium tin
oxide powder; and dispersing the surface-modified indium tin oxide
powder in a solvent, and then mixing the dispersion solution with a
resin, wherein, a dry powder of the indium tin hydroxide exhibits a
bright yellow to persimmon (reddish brown or orange-red) color, the
pH is adjusted within the range of 4.0 to 9.3 by using a mixed
aqueous solution of the indium compound and the divalent tin
compound and simultaneously adding dropwise the mixed aqueous
solution and an aqueous alkali solution in an aqueous, and a peak
of the (222) plane in an X-ray diffraction chart has a relative
intensity of about 2,800 to 5,000 cps, and has half value width of
a peak of about 0.3 to 0.5.degree. in the surface-modified indium
tin oxide powder.
7. The method for producing a heat-ray shielding composition
according to claim 6, wherein the surface modification is performed
by heating/firing which is performed simultaneously with or after
drying of bright yellow to persimmon (reddish brown or orange-red)
indium tin hydroxide under a nitrogen atmosphere, or under an
atmosphere of nitrogen containing any one kind selected from the
group consisting of steam, alcohol and ammonia, and the
surface-modified indium tin oxide powder has a navy blue or cobalt
blue tone and a BET specific surface area of 40 m.sup.2/g or
more.
8. The method for producing a heat-ray shielding composition
according to claim 4, which performs, in the step of obtaining the
surface-modified indium tin oxide powder, a surface modification
treatment of any one of the following (I), (II) and (III): (I) a
co-precipitate of indium tin hydroxide is dried and fired by
heating at 250 to 800.degree. C. for 30 minutes to 6 hours under a
nitrogen atmosphere, a nitrogen atmosphere containing an alcohol,
or a nitrogen atmosphere containing ammonia, (II) a co-precipitate
of indium tin hydroxide is dried overnight at 100.degree. C. to
200.degree. C. under an air atmosphere, and then fired by heating
at 250 to 800.degree. C. for 30 minutes to 6 hours under a nitrogen
atmosphere, a nitrogen atmosphere containing an alcohol, or a
nitrogen atmosphere containing ammonia; and (III) a co-precipitate
of indium tin hydroxide is dried and fired under an air atmosphere,
and then heat-treated at 250 to 800.degree. C. for 30 minutes to 6
hours under a nitrogen atmosphere, a nitrogen atmosphere containing
an alcohol, or a nitrogen atmosphere containing ammonia.
9. The method for producing a heat-ray shielding composition
according to claim 5, which performs, in the step of obtaining the
surface-modified indium tin oxide powder, a surface modification
treatment of any one of the following (I), (II) and (III): (I) a
co-precipitate of indium tin hydroxide is dried and fired by
heating at 250 to 800.degree. C. for 30 minutes to 6 hours under a
nitrogen atmosphere, a nitrogen atmosphere containing an alcohol,
or a nitrogen atmosphere containing ammonia, (II) a co-precipitate
of indium tin hydroxide is dried overnight at 100.degree. C. to
200.degree. C. under an air atmosphere, and then fired by heating
at 250 to 800.degree. C. for 30 minutes to 6 hours under a nitrogen
atmosphere, a nitrogen atmosphere containing an alcohol, or a
nitrogen atmosphere containing ammonia; and (III) a co-precipitate
of indium tin hydroxide is dried and fired under an air atmosphere,
and then heat-treated at 250 to 800.degree. C. for 30 minutes to 6
hours under a nitrogen atmosphere, a nitrogen atmosphere containing
an alcohol, or a nitrogen atmosphere containing ammonia.
Description
TECHNICAL FIELD
The present invention relates to a heat-ray shielding composition
having excellent heat-ray shielding effect, and a method for
producing the same, and more particularly to a heat-ray shielding
composition having excellent heat-ray shielding effect, which
contains a heat-ray shielding material of a co-precipitated indium
tin hydroxide having a bright yellow to persimmon (reddish brown or
orange-red) tone, or an indium tin hydroxide obtained by
surface-modifying an indium tin oxide powder having the above color
tone, and a method for producing the same.
This application claims priority on Japanese Patent Application No.
2009-248627 filed on Oct. 29, 2009 in Japan and Japanese Patent
Application No. 2010-171192 filed on Jul. 29, 2010 in Japan, the
disclosure of which is incorporated by reference herein.
BACKGROUND ART
Indium tin oxide (referred to as ITO) has been known as a heat-ray
shielding material. There has hitherto been known, as a method for
producing an ITO powder, a method in which an indium-containing
aqueous solution is mixed with a tin-containing aqueous solution to
co-precipitate indium tin hydroxide, and firing the obtained
co-precipitate.
For example, Japanese Unexamined Patent Application, First
Publication No. Hei 6-295315 (Patent Literature 1) describes a
method for producing an indium tin hydroxide in which indium metal
is dissolved in nitric acid and a mixed aqueous solution with an
aqueous tin tetrachloride solution (SnCl.sub.4) is concentrated
while heating. Japanese Patent No. 2,715,859 (Patent Literature 2)
describes a production method in which an aqueous indium
trichloride solution is mixed with an aqueous tin tetrachloride
solution and the obtained mixed solution is added dropwise in an
aqueous ammonium hydrogen carbonate solution.
According to the production method of Patent Literature 1, white
indium tin hydroxide is obtained. According to the production
method of Patent Literature 2, the formed indium tin hydroxide also
exhibits a white color. Furthermore, it has been known that indium
hydroxide generally exhibits white color and tin hydroxide also
exhibits white color (Non Patent Literature 1, etc.).
It has been known that, in case of using an ITO powder as a
heat-ray shielding material, the powder preferably has a color tone
in which a<0 and b<0, and the ratio [(ab)/L] of the (ab)
value to the L value is 0.3 or more in the Lab colorimetric system,
so as to enhance heat-ray shielding properties (Japanese Unexamined
Patent Application, First Publication No. 2007-154152: Patent
Literature 3). However, a conventional ITO powder is inferior in
heat-ray shielding properties since the above (ab)/L ratio has a
small value.
Japanese Patent Application No. 2005-232399 (Patent Literature 4)
discloses an ITO powder whose powder has a color in which L=52 to
90, a=-5 to -0.1, and b=-4 to 30 in the Lab colorimetric system.
However, the ITO powder described in Examples thereof has not a
yellow-based tone, but has a dull color tone in which a=-5.8 to
-4.6 and b=-12 to 4.6. Japanese Patent Application No. 2003-215328
(Patent Literature 5) discloses an ITO powder in which L=52 to 80,
a=-10 to -0.1, and b=-14 to 20. However, the ITO powder does not
have a yellow-based tone and any production method thereof is not
described at all.
Japanese Patent Application No. 2005-322626 (Patent Literature 6)
describes an ITO powder whose powder has a color in which L=82 to
91, a=-8 to 2, and b=0 to 10 in the Lab colorimetric system.
However, the ITO powder is a white-based powder in which a white
needle-shaped indium obtained by concentrating an indium nitrate
solution is calcined and pores thereof are impregnated with tin
tetrachloride, followed by firing, and also the production method
is complicated.
CITATION LIST
Patent Literature
[Patent Literature 1]
Japanese Unexamined Patent Application, First Publication No. Hei
6-293515 [Patent Literature 2] Japanese Patent No. 2,715,859
[Patent Literature 3] Japanese Unexamined Patent Application, First
Publication No. 2007-154152 [Patent Literature 4] Japanese
Unexamined Patent Application, First Publication No. 2005-232399
[Patent Literature 5] Japanese Unexamined Patent Application, First
Publication No. 2003-215328 [Patent Literature 6] Japanese
Unexamined Patent Application, First Publication No.
2005-322626
Non Patent Literature
[Non Patent Literature 1]
Kagaku Daijiten (Encyclopedic Dictionary of Chemistry), 1st Edition
(Tokyo Kagaku Dozin Co., Ltd.), page 1169, page 1170
DISCLOSURE OF INVENTION
Technical Problem
The present invention provides a composition which is excellent in
heat-ray shielding effect compared with a conventional heat-ray
shielding material. The present invention provides a heat-ray
shielding composition having a heat-ray shielding effect enhanced
by using, as a heat-ray shielding material, an ITO powder having a
bright yellow to persimmon (reddish brown or orange-red) tone, or
an ITO powder obtained by surface-modifying a co-precipitated
indium tin oxide powder having a similar color tone, in place of a
conventional white-based ITO powder.
Solution to Problem
The present invention is directed to a heat-ray shielding
composition in which the above-mentioned problems have been solved
by the following constitutions. [1] A heat-ray shielding
composition including an indium tin oxide powder (ITO power) which
has a BET specific surface area of 40 m.sup.2/g or more and a navy
blue or cobalt blue (L=30 or less, a<0, b<0 in the Lab
colorimetric system) tone. [2] The heat-ray shielding composition
according to the above [1], wherein, when the dispersion solution
having the concentration of 0.7% by weight to 1.2% by weight of the
indium tin oxide powder is subjected to the measurement using a
cell having an optical path length of 1 mm, the following
measurement are obtained: a sunlight transmittance is 60% or less,
a visible light transmittance is 85% or more, and a haze is 0.5% or
less. [3] The heat-ray shielding composition according to the above
[1] or [2], wherein the indium tin oxide powder contained in the
heat-ray shielding composition is an indium tin oxide powder which
is surface-modified by firing indium tin hydroxide having a bright
yellow to persimmon (reddish brown or orange-red) tone, or an
indium tin oxide powder which is surface-modified by firing indium
tin oxide having a bright yellow to persimmon (reddish brown or
orange-red) tone.
The present invention is also directed to a method for producing a
heat-ray shielding composition with the following constitutions.
[4] A method for producing a heat-ray shielding composition, which
includes the steps of: using an indium compound and a divalent tin
compound, and co-precipitating an indium tin hydroxide whose dry
powder exhibits bright yellow to persimmon (reddish brown or
orange-red) color under the conditions of the pH of 4.0 to 9.3 and
a liquid temperature of 5.degree. C. or higher; drying and firing
the indium tin hydroxide to obtain a surface-modified indium tin
oxide powder; and dispersing the surface-modified indium tin oxide
powder in a solvent, and then mixing the dispersion solution with a
resin. [5] The method for producing a heat-ray shielding
composition according to the above [4]; wherein the surface
modification is performed by heating/firing which is performed
simultaneously with or after drying of bright yellow to persimmon
(reddish brown or orange-red) indium tin hydroxide under a nitrogen
atmosphere, or under an atmosphere of nitrogen containing any one
kind selected from the group consisting of steam, alcohol and
ammonia; and the surface-modified indium tin oxide powder has a
navy blue or cobalt blue tone and a BET specific surface area of 40
m.sup.2/g or more. [6] The method for producing a heat-ray
shielding composition according to the above [4] or [5], which
performs, in the step of obtaining the surface-modified indium tin
oxide powder, a surface modification treatment of any one of the
following (I), (II) and (III): (I) a co-precipitate of indium tin
hydroxide is dried and fired by heating at 250 to 800.degree. C.
for 30 minutes to 6 hours under a nitrogen atmosphere, a nitrogen
atmosphere containing an alcohol, or a nitrogen atmosphere
containing ammonia; (II) a co-precipitate of indium tin hydroxide
is dried overnight at 100.degree. C. to 200.degree. C. under an air
atmosphere, and then fired by heating at 250 to 800.degree. C. for
30 minutes to 6 hours under a nitrogen atmosphere, a nitrogen
atmosphere containing an alcohol, or a nitrogen atmosphere
containing ammonia; and (III) a co-precipitate of indium tin
hydroxide is dried and fired under an air atmosphere, and then
heat-treated at 250 to 800.degree. C. for 30 minutes to 6 hours
under a nitrogen atmosphere, a nitrogen atmosphere containing an
alcohol, or a nitrogen atmosphere containing ammonia.
Advantageous Effects of Invention
Unlike a conventional white indium tin hydroxide, the heat-ray
shielding composition of the present invention contains
surface-modified indium tin oxide powder obtained by heat-treating
a co-precipitated indium tin hydroxide having a bright yellow to
persimmon (reddish brown or orange-red) tone. This surface-modified
indium tin oxide powder has high crystallinity. Therefore, when the
surface-modified indium tin oxide powder is mixed with a resin to
form a film, the obtained film has a high visible light
transmittance, excellent transparency and high conductivity, and
also a film whitening phenomenon is suppressed. This
surface-modified indium tin oxide powder is excellent in heat-ray
shielding effect and can form a film having a low sunlight
transmittance while maintaining high transparency.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph showing an X-ray diffraction pattern of an ITO
powder of No. 1 in Table 1 after firing in atmospheric air.
FIG. 2 is a partially enlarged view of FIG. 1.
FIG. 3 is a graph showing an X-ray diffraction pattern of a
co-precipitated indium tin hydroxide of No 1 in Table 1.
FIG. 4 is a graph showing an X-ray diffraction pattern of an ITO
powder of No. 9 in Table 1 after firing in atmospheric air.
FIG. 5 is a partially enlarged view of FIG. 4.
FIG. 6 is a graph showing an X-ray diffraction pattern of a
co-precipitated indium tin hydroxide of No 9 in Table 1.
FIG. 7 is a TEM micrograph of a co-precipitated indium tin
hydroxide of No. 1 in Table 1.
FIG. 8 is a TEM micrograph of a co-precipitated indium tin
hydroxide of No. 9 in Table 1.
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be specifically
described below by way of Examples.
[Heat-Ray Shielding Composition]
The heat-ray shielding composition of the present embodiment is a
heat-ray shielding composition including an indium tin oxide powder
which has a BET specific surface area of 40 m.sup.2/g or more and a
navy blue or cobalt blue (L=30 or less, a<0, b<0 in the Lab
colorimetric system) tone (hereinafter referred to as a ITO
powder).
The heat-ray shielding composition of the present embodiment is
preferably a composition having a heat-ray shielding effect in
which a sunlight transmittance is 60% or less, a visible light
transmittance is 85% or more, and a haze is 0.5% or less, when a
dispersion solution containing an ITO powder in a concentration of
0.7% by weight to 1.2% by weight is subjected to the measurement
using a cell having an optical path length of 1 mm.
[Production of Heat-Ray Shielding Material]
The ITO powder contained in the heat-ray shielding composition of
the present embodiment is preferably an ITO powder in which indium
tin hydroxide having a bright yellow to persimmon (reddish brown or
orange-red) tone is surface-modified by firing, or ITO having the
above color tone is surface-modified, and such an ITO powder can be
produced by the following method.
Indium and tin in the solution are precipitated in the presence of
an alkali to form a co-precipitated hydroxide of indium and tin. At
this time, it is possible to precipitate a co-precipitated
hydroxide of indium and tin, whose dry powder has a bright yellow
to persimmon (reddish brown or orange-red) tone by adjusting the pH
of the solution within a range from 4.0 to 9.3, and preferably from
6.0 to 8.0, and adjusting a liquid temperature within a range of
5.degree. C. or higher, preferably from 10.degree. C. to 80.degree.
C., and more preferably from 10.degree. C. to 60.degree. C. using a
divalent tin compound (SnCl.sub.2.2H.sub.2O, etc.). There is no
particular limitation on the reaction time, and the reaction time
may be from about 10 minutes to 240 minutes. The obtained hydroxide
having a bright yellow to persimmon (reddish brown or orange-red)
tone is excellent in crystallinity compared with a conventional
white indium tin hydroxide. Indium trichloride (InCl.sub.3) can be
used as indium.
When a tetravalent tin compound (SnCl.sub.4, etc.) is used, a white
precipitate is formed and a precipitate having a bright yellow to
persimmon (reddish brown or orange-red) tone is not formed. When
the pH is lower than 4.0 (acidic side) or higher than 9.3 (alkali
side), a pale yellowish white precipitate is formed and a
precipitate having a bright yellow to persimmon (reddish brown or
orange-red) tone is not formed. Any of a white precipitate by a
tetravalent tin compound and the above-mentioned yellowish-white
precipitate has low crystallinity compared with a precipitate
having a bright yellow to persimmon (reddish brown or orange-red)
tone and it is impossible to obtain an ITO powder having high
crystallinity like the present embodiment even when these
precipitates are fired. Since tin tetrachloride is used in the
production method of Patent Literature 1, a white indium tin
hydroxide precipitate is formed and a precipitate having a bright
yellow to persimmon (reddish brown or orange-red) tone is not
formed.
In order to adjust the hydrogen-ion exponent (pH) within a range
from 4.0 to 9.3 upon reaction, for example, the pH may be adjusted
within the above range by using a mixed aqueous solution of indium
trichloride (InCl.sub.3) and tin dichloride (SnCl.sub.2.2H.sub.2O)
and simultaneously adding dropwise the mixed aqueous solution and
an aqueous alkali solution. Alternatively, the above mixed solution
is added dropwise in an aqueous alkali solution. As the aqueous
alkali solution, ammonia water [NH.sub.3 water], ammonium hydrogen
carbonate water [NH.sub.4HCO.sub.3 water] and the like may be
used.
There is no particular limitation on the mixed aqueous solution, it
is possible to use an aqueous solution containing 0.01 to 5 mol/L
of an indium compound and Sn in the proportion of 1 to 20 mol % in
terms of a molar ratio of Sn/(In+Sn) of a tin compound.
Specifically, as shown in Examples 1 to 2 (Nos. 1 to 3), a
precipitate whose dry powder has a bright yellow to persimmon
(reddish brown or orange-red) tone is formed at pH 7 of the
solution and a liquid temperature of 10.degree. C. to 60.degree. C.
using tin dichloride. On the other hand, as shown in Comparative
Example 1 (No. 7), a pale yellowish white precipitate is formed at
pH of lower than 4.0 (pH 3.0) and, as shown in Comparative Example
2 (No. 8), a pale yellowish white precipitate is similarly formed
at pH of 9.3 or higher (pH 9.5). Therefore, in order to form a
co-precipitated indium tin hydroxide having a bright yellow to
persimmon (reddish brown or orange-red) tone, the pH is suitably
within a range of from 4.0 to 9.3. The pH becomes closer to
neutral, a persimmon (reddish brown or orange-red) color may
develop. Furthermore, when tin tetrachloride (SnCl.sub.4) is used
as shown in Comparative Example 3 (No. 9), a white precipitate is
formed and a precipitate, which has a bright yellow to persimmon
(reddish brown or orange-red) tone and also high crystallinity is
not formed.
After formation of the above-mentioned co-precipitated indium tin
hydroxide, the co-precipitate is washed with pure water, washed
until resistivity of the supernatant liquid becomes 5,000 .OMEGA.cm
or more, and preferably 50,000 .OMEGA.cm or more, and then the
above-mentioned co-precipitate is subjected to solid-phase
separation and the above co-precipitate is recovered. When the
resistivity of the supernatant liquid is less than 5,000 .OMEGA.cm,
impurities such as chlorine are not sufficiently removed and thus a
high-purity indium tin oxide powder cannot be obtained.
The dry powder of the above-mentioned indium tin hydroxide has a
bright yellow to persimmon (reddish brown or orange-red) tone and
L=80 or less, a=-10 to +10, b=+26 or more in the Lab colorimetric
system. For example, in Examples 1 to 6 (No. 1 to No. 6), L=60.3 to
75.1, a=-2.3 to +4.2, and b=+21.9 to +32.2. By the way,
precipitates of Comparative Examples 1 to 3 (No. 7 to 9) are
white-based precipitates in which L=91 to 100.
An ITO powder (In--Sn oxide powder) can be obtained by drying and
firing the above-mentioned indium tin hydroxide. In the step of
from drying to firing, for example, the indium tin hydroxide may be
dried by heating at 100 to 200.degree. C. for 2 to 24 hours in
atmospheric air and then fired by heating at 250.degree. C. or
higher, and preferably 400.degree. C. to 800.degree. C. for 1 to 6
hours. The hydroxide remains as it is at 250.degree. C. or lower
and is not converted into an oxide. Indium tin hydroxide is
oxidized by this firing treatment, and thus an indium tin oxide
powder having a bright yellow to persimmon (reddish brown or
orange-red) tone can be obtained.
The above-mentioned ITO powder subjected to firing treatment in
atmospheric air has a bright yellow to persimmon (reddish brown or
orange-red) tone. Specifically, L=80 or less, a=-10 to +10, and
b=+26 or more in the Lab colorimetric system. For example, in
Examples 1 to 6 (No. 1 to No. 6), L=56.6 to 67.1, a=-1.2 to +2.1,
and b=+29.5 to +31.5. On the other hand, a white-based indium tin
hydroxide is fired in atmospheric air to form an olive-green powder
in which a value is -5 or less in the Lab colorimetric system, as
shown in Comparative Example.
The above-mentioned ITO powder is a fine powder having a specific
surface area of 55 m.sup.2/g or more, and preferably 60 m.sup.2/g
or more. Specifically, ITO powders of Examples 1 to 5 have the BET
specific surface area of 60 m.sup.2/g to 85 m.sup.2/g, while ITO
powders of Comparative Examples 1 to 3 have a BET specific surface
area of 45 m.sup.2/g to 48 m.sup.2/g, and thus of Examples 1 to 5
are fine powders having noticeably larger specific area compared
with Comparative Examples 1 to 3.
The ITO powder having a bright yellow to persimmon (reddish brown
or orange-red) tone has high crystallinity. For example, in case of
an ITO powder No. 1 of Example A, as shown in FIG. 1 and FIG. 2, a
peak of the (222) plane in an X-ray diffraction chart has a large
relative intensity (about 3,000 cps) and a half value width thereof
is less than 0.6.degree. (specifically, 0.47.degree.). On the other
hand, an ITO powder No. 9 of Comparative Example A is obtained by
firing a white indium tin hydroxide and has an olive-green color.
As shown in FIG. 4, a peak of the (222) plane in an X-ray
diffraction chart has a relative intensity of 2,500 cps or less and
a half value width thereof is more than 0.6.degree. (specifically,
0.65.degree.). As mentioned above, the ITO powder used in the
present embodiment has a half value width which is considerably
less than that of an ITO powder of Comparative Example, and is
therefore a powder having a high crystallinity.
In the above-mentioned ITO powder having a bright yellow to
persimmon (reddish brown or orange-red) tone, it is preferred that
a peak of the (222) plane in an X-ray diffraction chart has a
relative intensity of about 2,600 to 4,000 cps and a half value
width thereof is about 0.3 to 0.6.degree.
In a drying and firing treatment of the above-mentioned
co-precipitated indium tin hydroxide (co-precipitated In--Sn
hydroxide) or a drying and firing treatment of the above-mentioned
indium tin oxide (In--Sn oxide), the ITO powder can be subjected to
a surface modification treatment. The conductivity can be improved
and also transparent conductivity effect can be enhanced by the
surface treatment.
The surface modification treatment of the following (I), (II) and
(III) can be performed at each stage simultaneously with drying, or
during or after firing. A surface-modified ITO powder can be
obtained by the surface modification treatment of the following
(I), (II) and (III): (I) the above-mentioned indium tin hydroxide
is dried and fired by heating at 250 to 800.degree. C. for 30
minutes to 6 hours under a nitrogen atmosphere, a nitrogen
atmosphere containing an alcohol, or a nitrogen atmosphere
containing ammonia, (II) the above-mentioned indium tin hydroxide
is dried overnight at 100.degree. C. to 200.degree. C. under an air
atmosphere to obtain a dried indium tin hydroxide. The dried indium
tin hydroxide is fired by heating at 250 to 800.degree. C. for 30
minutes to 6 hours under a nitrogen atmosphere, a nitrogen
atmosphere containing an alcohol, or a nitrogen atmosphere
containing ammonia; and (III) the above-mentioned indium tin
hydroxide is dried and fired under an air atmosphere, and then
heat-treated at 250 to 800.degree. C. for 30 minutes to 6 hours
under a nitrogen atmosphere, a nitrogen atmosphere containing an
alcohol, or a nitrogen atmosphere containing ammonia.
In the above-mentioned (III), the above-mentioned indium tin
hydroxide may be dried and fired at 250.degree. C. or higher under
an air atmosphere to obtain a dried indium tin oxide, and then the
obtained indium tin oxide may be heat-treated at 250 to 800.degree.
C. for 30 minutes to 6 hours under a nitrogen atmosphere, a
nitrogen atmosphere containing an alcohol, or a nitrogen atmosphere
containing ammonia.
The nitrogen atmosphere may contain any one kind selected from the
group consisting of steam, alcohol and ammonia.
The above-mentioned surface-modified ITO powder has a BET specific
surface area of 40 m.sup.2/g or more, preferably 55 m.sup.2/g or
more, and more preferably 55 to 80 m.sup.2/g, and has a navy blue
or cobalt blue color. Specifically, the surface-modified ITO powder
has a navy blue or cobalt blue tone in which L=30 or less, a<0,
b<0 in the Lab colorimetric system.
Since the surface-modified ITO powder is fine and also has high
crystallinity, when a film or a sheet is formed by mixing with a
resin, the obtained film or a sheet can be obtained high
transparency and excellent conductivity. When the surface-modified
ITO powder is used as a heat-ray shielding material, excellent
heat-ray shielding effect can be obtained.
In the surface-modified ITO powder, it is preferred that a peak of
the (222) plane in an X-ray diffraction chart has a relative
intensity of about 2,800 to 5,000 cps, and also has half value
width of a peak of about 0.3 to 0.5.degree..
The heat-ray shielding composition of the present embodiment
contains the surface-modified ITO powder.
The heat-ray shielding composition of the present embodiment is
produced, for example, by the following method.
The surface-modified ITO powder is dispersed in a dispersion
solvent to obtain a dispersion solution. There is no particular
limitation on dispersion solvent, and it is possible to use a
dispersion solvent composed of one or more kinds selected from the
group consisting of distilled water, triethylene
glycol-di-2-ethylhexanoate, anhydrous ethanol, phosphoric acid
polyester, 2-ethylhexanoic acid, 2,4-pentanedion, toluene, methyl
ethyl ketone, methyl isobutyl ketone, cyclohexanone, an acrylic
monomer, N-methylpyrrolidone, isopropyl alcohol, ethylene glycol,
propylene glycol and butanol.
The dispersion solution is mixed with a resin such as acryl,
polyimide, a phenol resin, polyvinyl alcohol or butyral to obtain a
heat-ray shielding composition.
There is no particular limitation on the amount of the heat-ray
shielding composition in the surface-modified ITO powder. The
heat-ray shielding composition is preferably prepared so that the
amount of ITO in the heat-ray shielding composition is adjusted
within a range from 0.01 to 90% by weight, and more preferably from
0.1 to 85% by weight. The content depends on the film thickness of
the heat-ray shielding composition. For example, in case of a
compound having a film thickness of 2 .mu.m, when the amount of the
surface-modified ITO powder is 1% by weight or more, a composition
having excellent heat-ray shielding effect can be provided. On the
other hand, when the amount of the ITO powder is 90% by weight or
less, the film strength can be maintained. There is also a method
in which the film strength is obtained by overcoating on a
composition composed of only an ITO powder.
Specifically, in the heat-ray shielding composition of the present
embodiment, when the concentration of the ITO powder of 0.7% by
weight to 1.2% by weight in the composition is measured using a
cell having an optical path length of 1 mm, the composition may be
a composition which has high heat-ray shielding effect with a high
sunlight transmittance of 60% or less and has high transparency
with a visible light transmittance of 85% or more, and is also less
hazy with a haze of 0.5% or less.
EXAMPLES
Examples of the present embodiment will be shown below, together
with Comparative Examples. X-ray diffraction pattern, specific
surface area and color tone (Lab values) of the ITO powder were
measured by the following methods.
[X-Ray Diffraction Pattern]
X-ray diffraction pattern was measured using a powder X-ray
diffractometer, manufactured by Rigaku Corporation (product name:
MiniFlexII).
[BET Specific Surface Area]
BET specific surface area was measured using a high-speed surface
area analyzer (SA-1100), manufactured by SIBATA SCIENTIFIC
TECHNOLOGY LTD.
[Color Tone]
Lab values were measured using a color computer (SM-T),
manufactured by SUGA TEST INSTRUMENTS CO., LTD.
[ITO powder: Sample No. 1]
An aqueous indium chloride (InCl.sub.3) solution (containing 18 g
of In metal) (50 mL) was mixed with 3.6 g of tin dichloride
(SnCl.sub.22H.sub.2O) and the obtained mixed aqueous solution and
an aqueous ammonia (NH.sub.3) solution were simultaneously added
dropwise in 500 ml of water. After adjusting to pH 7, the mixture
was reacted at a liquid temperature of 30.degree. C. for 30
minutes. The thus obtained precipitate was repeatedly subjected to
inclination washing with ion-exchange water. After resistivity of
the supernatant liquid reaches 50,000 .OMEGA.cm or more, a
precipitate (In/Sn co-precipitated hydroxide) was separated by
filtration to obtain a co-precipitated indium tin hydroxide whose
dry powder has a persimmon tone.
An X-ray diffraction pattern of the co-precipitated indium tin
hydroxide is shown in FIG. 3. A TEM (transmission electron
microscope) micrograph of the co-precipitated hydroxide powder is
shown in FIG. 7. As is apparent from FIG. 7, the co-precipitated
hydroxide powder has a clear crystal shape and thus the
co-precipitated hydroxide powder has high crystallinity.
The solid-liquid separated indium tin hydroxide was dried overnight
at 110.degree. C., fired at 550.degree. C. for 3 hours in
atmospheric air, and then an aggregate was disentangled by grinding
to obtain about 25 g of an ITO powder having a bright yellow
color.
Lab values and a specific surface area of the obtained ITO powder
are shown in Table 1.
The above-mentioned ITO powder (25 g) was impregnated by dipping in
a surface treatment liquid prepared by mixing anhydrous ethanol
with distilled water (in a mixing ratio of 95 parts by weight of
ethanol:5 parts by weight of distilled water) and then placed in a
glass petri dish and heated at 330.degree. C. for 2 hours under a
nitrogen gas atmosphere thereby performing a surface modification
treatment. A color tone (L, a, b) and a BET value of the ITO powder
are shown in Table 1. An X-ray diffraction pattern of the ITO
powder is shown in FIG. 1. Furthermore, a partially enlarged view
in the vicinity of a peak of the (222) plane is shown in FIG. 2. As
shown in the drawing, it was confirmed that the ITO powder has a
large relative intensity (about 3,000 cps), a half value width of a
peak of 0.47.degree. and high crystallinity. As shown in the X-ray
diffraction pattern, a crystal system of the ITO powder is a cubic
system.
[ITO Powder: Samples No. 2 to 3]
In the same manner as in Example 1, except that a liquid
temperature of a mixed solution was adjusted to 10 and 60.degree.
C., an ITO power was obtained. The results of the ITO powder are
shown in Table 1.
[ITO powder: Samples No. 4 to 5]
In the same manner as in Example 1, except that the pH of a mixed
solution was adjusted to 4.5 and 8.5 by adjusting the addition
amount of the aqueous alkali solution and that the liquid
temperature was changed to 30.degree. C., an ITO power was
obtained. The results of the ITO powder are shown in Table 1.
[ITO Powder: Samples No. 6]
In the same manner as in Example 1, except that an aqueous ammonium
hydrogen carbonate (NH.sub.4HCO.sub.3) solution was used as the
aqueous alkali solution, an ITO power was obtained. Precipitation
conditions, a color tone of a precipitate, a color tone and a
specific surface area of the ITO powder, and the results of a
surface treatment are shown in Table 1.
[ITO Powder: Comparative Sample No. 7]
In the same manner as in Example 1, except that the pH of a mixed
solution was adjusted to 3.0 by adjusting an addition amount of an
aqueous alkali solution, a co-precipitated indium tin hydroxide was
obtained. A dry powder of the co-precipitated indium tin hydroxide
had a slightly yellowish white color. In the same manner as in
Example 1, the precipitate was treated to obtain an ITO powder. The
results of the ITO powder are shown in Table 1.
[ITO Powder: Comparative Sample No. 8]
In the same manner as in Example 1, except that the pH of a mixed
solution was adjusted to 9.5 by adjusting the addition amount of
the aqueous alkali solution and that the liquid temperature was
changed to 10.degree. C., a co-precipitated indium tin hydroxide
was obtained. The dry powder of the co-precipitated indium tin
hydroxide had a slightly yellowish white color. In the same manner
as in Example 1, the precipitate was treated to obtain an ITO
powder. The results of the ITO powder are shown in Table 1.
[ITO Powder: Comparative Sample No. 9]
Using tin tetrachloride (aqueous SnCl.sub.4 solution having a
concentration of 55%) as a tin compound, 14.4 g of the aqueous
SnCl.sub.4 solution was mixed with 90 mL of an aqueous indium
chloride (InCl.sub.3) solution (containing 35 g of In metal) and
the pH of a mixed aqueous solution was adjusted to 8 by adding 0.6
L of an aqueous alkali solution containing 190 g of ammonium
hydrogen carbonate (NH.sub.4HCO.sub.3) to the mixed aqueous
solution, and then the mixture was reacted at a liquid temperature
of 30.degree. C. for 30 minutes. The thus obtained precipitate was
repeatedly subjected to inclination washing with ion-exchange
water. After resistivity of the supernatant liquid reaches 50,000
.OMEGA.cm or more, a co-precipitated indium tin hydroxide was
separated by filtration. The obtained co-precipitated indium tin
hydroxide had a white color. An X-ray diffraction pattern of the
co-precipitated indium tin hydroxide is shown in FIG. 6. A TEM
micrograph of the co-precipitated hydroxide powder is shown in FIG.
8. As is apparent from FIG. 8, the co-precipitated hydroxide powder
has an unclear crystal shape when compared with the powder (No. 1
of Example A) in FIG. 7. The co-precipitated indium tin hydroxide
was dried overnight at 110.degree. C., fired at 550.degree. C. for
3 hours in atmospheric air, and then an aggregate was disentangled
by grinding to obtain about 44 g of an ITO powder. The
above-mentioned ITO powder (25 g) was impregnated by dipping in a
surface treatment liquid prepared by mixing anhydrous ethanol with
distilled water (in a mixing ratio of 95 parts by weight of
ethanol:5 parts by weight of distilled water) and then placed in a
glass petri dish and heated at 330.degree. C. for 2 hours under a
nitrogen gas atmosphere.
Lab values and a specific surface area of the ITO powder are shown
in Table 1. An X-ray diffraction pattern of the ITO powder is shown
in FIG. 4. Furthermore, a partially enlarged view in the vicinity
of a peak of the (222) plane is shown in FIG. 5. As shown in the
drawing, it was confirmed that the ITO powder has a relative
intensity of less than about 2,500 cps, a half value width of a
peak of 0.65.degree. and crystallinity lower than that of the ITO
powder No. 1 of Example A.
As shown in Table 1, in any samples (No. 1 to No. 6) in preferred
range of the present embodiment, a co-precipitated indium tin
hydroxide having a bright yellow to persimmon tone is formed. When
the pH deviates from the above range, as shown in Comparative
Examples 1 to 3, a yellowish white precipitate is formed, and also
the BET value decreases and the L value is more than 40 in the Lab
colorimetric system of the powder after subjecting to a
modification treatment. Furthermore, a problem such as whitening is
likely to arise when formed into a coating film, resulting in poor
heat-ray shielding properties. On the other hand, surface-modified
ITO powders (No. 1 to No. 6) of the present embodiment have a
specific surface area of 50 m.sup.2/g or more and most of powders
are fine powders having a specific surface area of 55 m.sup.2/g or
more. Therefore, it is possible to form a film having high visible
light transmittance when a film is formed by mixing with a
resin.
The surface-modified ITO powders (No. 1 to No. 6) of the present
embodiment are powders having a navy blue color in which L<30,
a<0, and b<0 in the Lab colorimetric system. Since a ratio
[(ab)/L] of the (ab) value to the L value is 0.3 or more (0.8 or
more in case of No. 2 to No. 6 in Table 1), excellent heat-ray
shielding effect can be obtained when used as a heat-ray shielding
material.
As shown in FIG. 1, FIG. 2 and FIG. 7, a co-precipitated hydroxide
having a bright yellow color has high crystallinity of a hydroxide.
It is possible to obtain an ITO powder having high specific surface
area and high crystallinity by using the co-precipitated indium
hydroxide having high crystallinity. A heat-ray shielding
composition using the ITO powder can obtain high transparency and
excellent sunlight shielding properties.
TABLE-US-00001 TABLE 1 Example A Comparative Example A Sample No. 1
No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 No. 9 In raw material
Incl.sub.3 Incl.sub.3 Incl.sub.3 Incl.sub.3 Incl.sub.3 Inc- l.sub.3
Incl.sub.3 Incl.sub.3 Incl.sub.3 Sn raw material SnCl.sub.2
SnCl.sub.2 SnCl.sub.2 SnCl.sub.2 SnCl.sub.2 SnC- l.sub.2 SnCl.sub.2
SnCl.sub.2 SnCl.sub.4 Aqueous alkali solution NH.sub.3 NH.sub.3
NH.sub.3 NH.sub.3 NH.sub.3 NH.sub.4HCO.sub.3 N- H.sub.3 NH.sub.3
NH.sub.4HCO.sub.3 Mixed solution pH 7 7 7 4.5 8.5 7 3.0 9.5 8
Liquid temperature 30.degree. C. 10.degree. C. 60.degree. C.
30.degree. C. 30.degree. C. 30.degree. C. 30.degree. C. 10.degree.
C. 30.degree. C. Color tone of Persimmon Bright Bright Bright
Persimmon Bright Yellowish- Y- ellowish- White co-precipitate
yellow yellow yellow yellow white white L 75.1 70.0 68.3 66.0 65.0
60.3 91 95 100 a -1.5 1.1 1.5 -2.3 4.2 0.4 0.2 0.1 0.1 b 30.7 31.2
31.2 32.2 21.9 31.0 R5.3 2.1 -0.2 Color tone of ITO powder Bright
Bright Bright Bright Bright Bright Olive- Olive- Olive- fired in
atmospheric air yellow yellow yellow yellow yellow yellow green
green green L 60.1 58.3 56.0 62.3 67.1 57.2 82.5 77.8 77.8 a 0.4
1.1 -0.8 -1.2 1.2 2.1 -7.1 -7.4 -8.7 b 30.8 31.5 29.5 31.2 30.8
29.7 16.3 17.8 27.9 BET value of ITO powder 71 85 60 72 72 68 48 45
45 (m.sup.2/g) ITO powder after Navy blue Navy blue Navy blue Navy
blue Navy blue Navy blue Light blue Light blue Light blue
modification treatment L 21.3 29.1 27.4 29.6 26.5 27.9 53.8 56.5
44.5 a -2.8 -2.1 -2.2 -4.2 -3.8 -3.3 -4.0 -5.3 -3.4 b -2.3 -12.0
-11.0 -7.2 -6.1 -7.8 -14.1 -14.3 -1.0 BET value of ITO powder 55 71
50 55 56 62 29 27 35 after modification treatment (m.sup.2/g)
(Note): SnCl.sub.2 is SnCl.sub.2.cndot.2H.sub.2O, co-precipitate is
co-precipitated indium tin hydroxide, and color tone of a
co-precipitate is a color tone of a dry powder, and yellowish-white
is slightly yellowish white color.
[Test of Heat-Ray Shielding Properties or the Like]
With respect to dispersion solutions of ITO powders (No. 1, No. 6,
No. 7 and No. 8) shown in Table 1, a visible light transmittance (%
Tv), a sunlight transmittance (% Ts), a haze and a reflective
yellowness index (YI) were measured. The details are shown below
(Example B and Comparative Example B). The visible light
transmittance (% Tv), sunlight transmittance (% Ts), haze and
reflective yellowness index (YI) were measured by the following
methods.
Example B
ITO powders (20 g) of samples No. 1 and No. 6 shown in Table 1 were
dipped and dispersed in a mixed solution of distilled water (0.020
g), triethylene glycol-di-2-ethylhexanoate [3G] (23.8 g), anhydrous
ethanol (2.1 g), phosphoric acid polyester (1.0 g), 2-ethylhexanoic
acid (2.0 g) and 2,4-pentanedion (0.5 g).
[Measurement of Spectral Characteristics]
The thus prepared dispersion solution was diluted with triethylene
glycol-di-2-ethylhexanoate until the amount of ITO powder reaches
0.7% by mass. With respect to the sample No. 6, the amount of the
ITO powder was adjusted to 0.7% by weight, 0.9% by weight, 1.2% by
weight and 1.4% by weight. The diluted solution was charged in a
glass cell having an optical path length of 1 mm Using a
self-registering spectrophotometer (U-4000, manufactured by
Hitachi, Ltd.), a visible light transmittance (% Tv) at 380 nm to
780 nm and a sunlight transmittance (% Ts) at 300 nm to 2,100 nm
were measured at normal temperature in accordance with the standard
(JIS R 3216-1998 (equivalent to ISO9050 1990)). The results are
shown in Table 2.
[Haze]
Using the dispersion solution diluted in the same manner as in case
of the sample for the measurement of spectral characteristics as a
sample, the sample was charged in a glass cell having an optical
path length of 1 mm Using a haze computer (HZ-2, manufactured by
SUGA TEST INSTRUMENTS CO., LTD.), a haze was measured at normal
temperature in accordance with the standard (JIS K 7136 (equivalent
to ISO 14782 1999)). The results are shown in Table 2.
[Reflective Yellowness Index (YI)]
Using the dispersion solution diluted in the same manner as in case
of the sample for the measurement of spectral characteristics as a
sample, 6.73 g of the diluted solution sample was charged in a
liquid cell for reflection (No. 15). Using a color computer (SM-T,
manufactured by SUGA TEST INSTRUMENTS CO., LTD.), a reflective
yellowness index (YI) was measured from a reflectance of visible
light (380 nm to 780 nm) in a state of being covered with a dark
box for shielding outdoor daylight in accordance with the standard
(JIS K 7105). The results are shown in Table 2.
The measurement was performed by the following equation:
YI=100(1.28X-1.06Z)/Y. where X, Y and Z are tristimulus values (XYZ
colorimetric system) of test samples in standard illuminant C. The
standard illuminant C is model illuminant obtained by approximation
of average daylight with a correlated color temperature of
6774.degree. K using a CIE (Comission Internationale de
l'Eclairage) standard light source formed by a tungsten light
source through a filter.
Comparative Example B
ITO powders (20 g) of samples No. 7 and No. 8 shown in Table 1 were
dispersed in the mixed solution similar to Example A. With respect
to the dispersion solution, the visible light transmittance (% Tv),
sunlight transmittance (% Ts), haze and reflective yellowness index
(YI) were measured. The results are shown in Table 2.
As shown in Table 2, since the heat-ray shielding composition of
the present embodiment composed of a dispersion solution of ITO
powders of samples No. 1 and No. 6 has high visible light
transmittance compared with samples No. 7 and No. 8 of Comparative
Example B and satisfactory crystallinity of the ITO powder,
sunlight transmittance is low and heat-ray shielding properties are
remarkably improved regardless of high visible light transmittance.
Furthermore, since samples No. 1 and No. 6 of the present
embodiment also have low haze value, even if the concentration of
ITO in the dispersion solution is increased by two times, the haze
value is 1% or less. Furthermore, the reflective yellowness index
(YI) has a small absolute value, and thus a less hazy film can be
formed.
On the other hand, in case of using ITO powders of samples Nos. 7
and 8, the visible light transmittance (% Tv) is low and the
sunlight transmittance (% Ts) is high because of low BET value. In
addition, the haze is drastically high.
TABLE-US-00002 TABLE 2 Comparative Example B Example B A1 A2 A3 A4
A5 B1 B2 Kind of powder No. 1 No. 6 No. 6 No. 6 No. 6 No. 7 No. 8
Concentration of 0.7 0.7 0.9 1.2 1.4 0.7 0.7 ITO in dispersion
solution (%) % Tv 88.5 90.9 88.4 85.0 82.8 84.1 84.0 % Ts 57.5 60.0
56.0 51.4 48.6 65.0 64.4 Haze (%) 0.35 0.31 0.37 0.48 0.54 5.01
1.01 YI -17.5 -17.1 -20.2 -24.2 -26.4 -- -30.1 (Note): Each of Nos.
1, 6, 7 and 8 denotes the ITO powder of the same number in Table 1.
Since sample No. 7 has high haze, the YI value was not
measured.
* * * * *